Screen printing machine



Nov. 17, 1942. SNYDER 2,302,152

SCREEN PRINTING MACHINE Filed Ma rch 16, 1940 3 Sheets-Sheet 1 Ji .1. 7 J

Nov. 17, 1942. SNYDER 2,302,152

SCREEN PRINTING MACHINE Filed March 16, 1940 3 Sheets-Sheet 2 NOV. 17, E K SNYDER SCREEN PRINTING MACHINE Filed March 16, 1940 3 Sheets-Sheet 3 Patented Nov. 17, 1942 2,302,152

UNITED STATES PATENT OFFICE,

SCREEN PRINTING MACHINE Ernest K. Snyder, Lynchburg, Va., assignor, by

mesne assignments, to Precision Finishing Ma.- chlne Corporation, Lynchburg, Va., a corporation of Virginia Application March 16, 1940, Serial No. 324,407

15 Claims. (Cl. 101--122)v I V This invention relates to improvements in plane of the axes of the conveyor roller and screen printing machines, and in this connecsqueegee showing means for heating the screen tion the term "printing" is employed to identify throughout a region anterior to the squeegee; the machine as to type and not to indicate any Figure '1 is a partial plan view showing one limitation of its use, for it is adapted not only end of the conveyor with means for electrically to the art of printing, but to the coating of heating that part of the conveyor which extends materials generally, the production of inlaid between the ends of the roller; and coatings, as in the manufactu e of linoleum and Figure 8 is an end view of they roller shown in the filling of plastic material into molds. in Figure 7.

The machine of the present invention is of Referring now in detail to the several figures,

that type in which a continuous screen moves the numeral I represents in general a table or into contact, in a fixed region, with the surface stand having the legs 2 and 3 and braces 4, and of a correspondingly moving workpiece which 5. Such structure is by way of example, and. may be a sheet of material or a mold, through has no essential part in the invention. which screen the fluent material is forced upon The main cooperating elements of the invensaid workpiece in said region of contact. tion are a conveyor which as. a whole. is desigw In this type of machine the fluent material nated by the reference character 6, and a screen is forced through the screen by squeegee means head, which may be of any desired shape, being such as a blade or roller, and the screen may here shown as of general triangular sha'pe'and be open throughout to produce a continuouszo denoted as a whole by the reference numeral], coating or clothed with'a stencil to produce a Referring to the conveyor, it comprises a pair design. of parallel rollers 8 and 9 mounted at remote One of the objects of the invention is to propoints beneath the table I in bearings 10 and vide a machine of the class described, inwhich H, the latter of which is fixed with respect to provision ismade for interchanging adjustments the table but the former of which is vertically by means of which exact registry between the adjustable. This adjustment permits the conscreen and the moving workpiece is obtained. veyor to be swung pivotally about the axis of Another object of the invention is to provide the roller 9. An endless conveyorbelt l2 passes an endless screen, which together with the supabout the rollers 8 and 9, its upper flight restporting rollers therefor can be removed or re- 0 me upon the table I. The bearing of theroller placed as a unit without changing the axial 9 is longitudinally slidable in aslot in the bracket relationship of the rollers. l3, while the hearing I ll of the roller 8 is rela- Still another object of the invention is to protively fixed insofar as its movement longitudivide meansfor heating the screen and thereby nally of the conveyor is concerned. This perheating the fluent materialwhich it carries inmits tightening of the conveyor belt and chain a region anterior to the squeegee. when such an adjustment is deemed desirable;

Other objects of the invention will appear as The means for elevating the bearings Ill comthe following description of a preferred and pracprises a pair of lifting jacks, each respectively tical embodiment thereof proceeds. inc ud ng threaded Stems l4 and I5 held against In the drawings which accompany and form rotation by being splined in a fixed guide [6 and a part of the following specification,and'throughthreadedly engaging the bore of a rotatable.

out the several figures of which the same charsleeve l1 carrying the respective gears l8 and acters of reference have been employed to desig- I9 at the upper end, said gears being connected nate identical parts: .by gears 20 and 2| at the ends of a connect- Figure l is a side elevation of a machine eming shaft 22. The lower end of the sleeve 'II bodying the principles of the invention; carries a gear 23 meshing with the worm 24 which Figure 2 is a longitudinal vertical section is actuated by a hand wheel 25.

through the machine; The necessity foradiusting the conveyor by Figure 3 is a vertical cross-section taken along swinging it about the axis of the roller 9 is to the line 3-3 of Figure 2; I permit stock of different thicknesses to passbe- Figure 4 is a perspective view showing a detail tween the screen head and conveyor while mainof construction; e taining the relative parallel relation of said con- Figure 5 is a vertical section showing a modiveyor to the bottom flight of the screen, as will fied form of squeegee; e presently appear. s

Figure 6 is a partial plan view taken in the It happens in the illustrated embodiment of the invention that the roller 8 is the driving element of the conveyor. Power is transmitted thereto from any source, by means such as the belt 28 passing over a pulley 21 on the shaft 28 of the roller 8, and as the tension of the belt 28 will vary in different positions of adjustment of the roller 8, a spring pressed idler 29 is provided for taking up any undue looseness of the belt.

The conveyor includes an endless belt l2 which is preferably a flexible metallic sheet. It is tightly held between the rollers 8 and 9, the latter being driven by chains 3| and 32 on sprockets 33 and 34 on opposite ends of the rollers 8 and 9. The conveyor belt is kept in taut bridging relation to the chains, preferably by being secured to the links of said chains by tenter hooks 35 carried by said links, and entering marginal apertures in the conveyor belt.

The screen head comprises a pair of upright frame members 38 and 31 connected by transverse rods 38. A trio of rollers, 38, 40 and 4|, are carried between the frame members 38 on shafts at the apices of the triangles, said rollers having sprockets 42, 43 and 44 at their opposite ends operatively embraced by the chains 45 and 46. The above structural unit is hereinafter referred to as the screen head, and is adapted to carry an endless screen belt 41 tightly stretched around the rollers, and being kept transversely taut between said rollers by means such as the tenter hooks 48, carried by the links of the chains, and which engage perforations in the margins of the screen. As will be observed in the upper part of Figure 3, the tenter hooks are so formed as to bring the plane of the screen into the pitch line of the chains.

The screen head occupies a fixed position on the table I, being pivotally mounted at one of its corners by means such as the trunnions 49 (see Figure 1) carried in bearings 50 fixed with respect to said table. The screen head is swingable about said trunnions. The rollers of the screen head are driven through interconnection with the driving shaft of the conveyor roller 8. This driving connection is effected by means of a laterally extended portion of the shaft of the roller 39, upon which extended portion is a gear 52 meshing with a gear 53. The gear 53 is freely mounted axially of the shaft of the conveyor roller 8 and may be connected or disconnected from said shaft by a clutch 53. Thus, at times when desired, the screen head may be declutched from the conveyor so that the latter may move while the screen on the screen head remains stationary.

The screen head is swingable about the trunnions 49 through an adjustment at its opposite end, said adjustment comprising a pair of lifting jacks 55 and 56 which may be similar in their construction and mode of interconnection to the lifting jacks l4 already described. The lifting jacks 55 and 56 are operated through the hand wheel 51. V

It may now be understood that in the normal operation of this printing machine the lower flight 58 of the screen, and the upper flight of the conveyor belt 12 travel in parallelism a distance apart just equal to or slightly greater than the thickness of the workpiece which as has hereinbefore been stated, may be a piece of sheet material or a mold, so that the upper face of the workpiece contacts the lower face of the screen or a stencil which may be mounted thereupon, or

be part thereof. When a workpiece of diiferent 75 thickness is employed, the conveyor and screen head must be adjusted so as to increase the width of the parallel space between the screen and the conveyor belt.

For example, when a thicker workpiece is to be used, the left hand end of the conveyor is dropped by lowering the bearings It). This, of course, produces a convergent space between the conveyor belt and the bottom flight 58 of the screen. Then the left hand end of the conveyor head is lowered by means of the jacks 55 and 58. This will restore a condition of parallelism between the bottom flight 58 and the conveyor belt, with a greater space between these members due to the fact that the conveyor and the screen head pivot about different axes.

The entire screen head may be bodily removed from the machine without removing or disturbing the screen of said screen head or any stencil which may be thereupon, so that the screen head may be in the minimum of time replaced by another screen head having a different screen or different stencil. This removal or replacement is readily effected by taking oil the caps 59 of the bearings which confine the trunnions 49 and by loosening the lock nuts 60 which hold the upper ends of the lifting jacks and 58 in the slotted recesses 6| in the otherwise free ends of the frame members 36 and 31 of the screen head. The trunnions may then be lifted out of the bearings 68 and the entire screen head slid to the right to release the members 36' and 31 from the lifting Jacks, whereupon the screen head may be bodily lifted off of the machine, the gear 52 readily unmeshing from the gear 53. When desired, the screen may be removed from the screen head by utilizing the reserve slack in the screen.

One of the salient features of this invention is the possibility of obtaining and maintaining nicety of alignment between the conveyor belt and the screen or stencil on the screen head which move at precisely the same speed when the machine is in operation. Perfect alignment is essential in printing, particularly in multi-color work where the same workpiece will be run several times beneath the same screen head or beneath different screen heads which may replace the original screen head. The same is true where the machine is employed to produce plastic inlaid patterns, as in the making of linoleum, also where the conveyor belt carries a mold with a plurality of depressions and a stencil on the screen is employed for filling these depressions with plastic. Accurate alignment is obtained in th following manner. The conveyor is provided with means constituting an index, this being in the present illustrative embodiment of the inven-- tion any one of a plurality of the lugs 82 which project from the surface of the conveyor belt. The workpiece is laid upon the conveyor belt against one of these indices. An appropriate stencil is then mounted upon the screen of the screen head and secured against slipping by being engaged'with the tenter hooks 48. The clutch 54 is then declutched and the screen with the superposed stencil shifted by hand until the stencil is properly and accurately aligned with the workpiece. The clutch 54 is then reengaged, and when the driving means is started, the conveyor belt with the workpiece and the screen with the stencil will move in unison, maintaining perfect alignment.

The material to be applied to the workpiece is wiped through the screen or through the screen and stencil, where a stenci1 is employed, by the squeegee 3, which is pivotally mounted on the screen head at 64 and is biased against the bottom flight 58 of the screen by pressure of the spring 65. Pressure of the squeegee 63 against the screen or screen and stencil causes the screen, with or without the stencil as the case may be, to make line contact with the workpiece at the point 66. The amount of fluent material which is wiped through the screen or the screen and stencil by the squeegee depends largely upon the thinness, that is to say, the viscosity of the plastic. In the case of printer's ink a very thin film will be wiped through upon the workpiece as it passes the point of line contact. Where the plastic is heavier, as would be the case in depositing an inlaid pattern upon the workpiece, or in the filling of a mold, the film squeezed through the screen or the screen and stencil by the squeegee will be thicker.

In the making of inlaid linoleums or in multicolor work, it is within the purview of the invention to have a plurality of screen heads arranged serially upon the same table, the workpiece passing successively beneath each.

Inasmuch as there is necessarily a small amount of lost motion in the pivotal connections of the links in chains, and it being highly desirable to minimize the effect of this lost motion in the operation of the present machine, the squeegee 84 is arranged as close to the driving roll 8 of the conveyor, as possible, so as to be affected by the lost motion in the minimum number of links of both the conveyor chains and those of the screen head.

In general, when dealing with the heavier or more viscous plastics, it is advantageous to apply them to the workpiece when in heated condition. Figure 6 illustrates a means for electrically heating that part of the screen anterior to the squeegee to which the supply of plastic is fed. In this form of the invention the squeegee may be in the form of a metallic roller 61, the metallic shaft 68 of which is mounted in bearings 69 or insulation material. The squeegee 61 is, therefore, out of metallic contact with any part of the machine, excepting the bottom flight 58 of the screen, which it engages. The shaft 68 is contacted by a brush l constituting one terminal of a force of electrical current. The shaft H of the roller 40 is also electrically insulated from the machine by means of insulation bearings I2, said shaft being engaged by the brush 13, the same being the other terminal of the electrical circuit. The circuit is completed between the squeegee 61 and the roller 40 by the bridging portion of the metallic screen 58. Either the roller 40 itself may be of metal. or the sprockets 43 which are in metallic continuity with the screen through the chains 45 and tenter hooks 48. Current passing through the screen heats it and the plastic which it carries.

In that form of the invention shown in Figures 7 and 8, it is the sprockets 43 which are electrically insulated from the rest of the machine by means of the annular rings 14 of insulation material which intervene between the rims of the sprockets and the hubs. The brushes l0 and 13 contact the chains which pass over the sprockets, the circuit being closed by the width of that portion of the screen 58 which extends between said sprockets.

Figure shows another means for heating the plastic, in which the squeegee roller Il may or may not be metallic, as desired, but is cored to form apertures in which the heating elements 18 are housed. Said elements would be connected to a source of current by means of insulated slip rings in metallic continuity with the heating elements and insulated from the machine.

These modes of heating the plastic are merely exemplary of other expedients which may be employed without transcending the scope of the invention.

The ends of the screen belt 41 are held together by a transverse bar 19 consisting of a pair of plates, one on the inside and the other on the outside of the screen, clamped together against the meeting margins of the screen as by the screws 80.

In Figure 2, I have shown scrapers 15 which keep clean the surfaces of the rollers 39 and 40 and return the plastic which collects upon them, to the main body of plastic resting upon the lower flight 58 of the stencil screen. I have also shown an adjustable bearing for the roller 4|, by means of which said roller may be lowered to loosen the screen and/or the stencil to permit the removal of either or both of these endless instrumentalities from the screen head. In Figure 1 I have shown means comprising a set screw 16 and lock nut for fixing the shiftable conveyor bearing II in any position of its chaintightening adjustment. 7

Generally, in printing or in applying inlaid patterns to sheet material, or in filling molds, stencils will be employed on the screen of the screen head. The machine is, however, equally adapted to applying a continuous undifferentiated coating to the workpiece. Where this-is to be done, the stencil is omitted and the fluent material wiped or forced by the squeegee directly through the unclouded screen. i

While I have in the above description disclosed what I believe to be a preferred and practical embodiment of the invention, it will be understood to those skilled in the art that the specific details of construction as described and illustrated are by way of illustration, and not to be construed as limiting the scope of the in-' vention which is defined in the appended claims.

What I claim as my invention is:

1. Screen printing machine comprising a belt conveyor having a planiform flight for movably supporting a workpiece, and a screen head superposed with respect thereto having a screen belt with a substantially planiform flight sub stantially parallel to the planiform flight of said conveyor, providing space for the workpiece therebetween, a transversely disposed squeegee pressing the inner surface of said screen belt to make line contact with the workpiece and force fluent material through said screen belt upon the workpiece, means for driving said conveyor, means for driving said screen belt positively from said conveyor whereby both said screen belt and conveyor are driven together at substantially thev same surface speed, and means to tilt said screen head to provide relative adjustment between said screen head and said conveyor for changing the distance between their substantially parallel flights to permit workpieces of different thick nesses to pass therethrough.

2. Screen printing machine comprising a. belt conveyor having a planiform flight for movably supporting a workpiece, and a screen head superposed with respect thereto having a screen belt with a substantially planiform fiight,-substantially parallel to the planiform night of said conveyor providing space for the workpiece therebetween, a transversely disposed squeegee pressing the inner surface of said screen belt to make line contact with the workpiece and force fluent material through said screen belt upon said workpiece, means for driving said conveyor, means for driving said screen belt positively from said conveyor, whereby both said screen belt and conveyor are driven together at substantially the same surface speed, said screen head and conveyor being noncoaxially pivoted at one and adjacent ends about parallel axes, and means for independently swingably adjusting said screen head and conveyor about their respective axes whereby they may be made to assume parallel relationship at various distances apart, to accommodate workpieces of different thickness.

3. Screen printing machine comprising a belt conveyor having a planiform flight for movably supporting a workpiece, and a screen head superposed with respect thereto having a screenbelt with a substantially planiform flight, substantially parallel to the planiform flight of said conveyor, providing space for the workpiece therebetween, trunnions at one end of said screen head swingably and removably supporting said screen head, means for driving said conveyor, means for driving said screen belt positively from said conveyor whereby both said screen belt and conveyor are driven together at substantially the same surface speed, the driving connection between said screen belt and conveyor including a pair of gears one carried by the opposite end of said screen head and freely unmeshable when said screen head is removed from said machine.

4. Screen printing machine comprising a belt conveyor having a planiform flight for removably supporting a workpiece, and a screen head superposed with respect thereto comprising side frame members having a screen belt revolubly supported therebetween with a substantially planiform flight substantially parallel to the planiform flight of said conveyor providing a space for th workpiece therebetween, a transversely disposed squeegee pressing the inner face of said screen belt to make line contact with the workpiece and force fluent material through said screen belt upon the workpiece, trunnions at one end of said frame members swingably and removably supporting said screen head, lifting jacks under the opposite ends of said frame members for tiltably adjusting said screen head about said trunnions, means for driving said conveyor, means for driving said screen belt positively from said conveyor whereby both said screen belt and conveyor are driven together at substantially the same surface speed, the driving connection between said screen belt and conveyor including a pair of gears, one carried by said screen head, freely unmeshing when the screen head is removed from the machine.

5. Screen printing machine, as claimed in claim 4, said conveyor being swingably supported at the the end adjacent the trunnions of said screen head and lifting jacks under the opposite end of said conveyor for swingably adjusting said conveyor relative to said screen head whereby the distance between their substantially parallel flights may be varied.

6. Screen printing machine comprising a belt conveyor having a planiform flight for movably supporting a workpiece, and a screen head superposed with respect thereto having a screen belt with a substantially planiform flight substantially parallel to the planiform flight of speed conveyor providing space for the workpiece therebetween, a transversely disposed squeegee pressing the inner face of said screen belt to make line contact with the workpiece and force fluent material through said screen belt upon said workpiece, means for driving said conveyor, means for driving said screen belt positively from said conveyor whereby both said screen belt and conveyor are driven at substantially the same surface speed, means for heating said screen belt and the fluent material thereupon, only in the region adjacent said squeegee.

7. Screen printing machine comprising a belt conveyor having a planiform flight for movably supporting a workpiece, and a screen head superposed with respect thereto having a screen belt with a substantially planiform flight substantially parallel to the planiform flight of speed conveyor providing space for the workpiece therebetween, a transversely disposed squeegee to make line contact with the workpiece and force fluent material through said screen belt upon said workpiece, means for driving said conveyor, means for driving said screen belt positively from said conveyor whereby both said screen belt and conveyor are driven at substantially the same surface speed, and means for heating said screen belt in a region posterior to said squeegee, with reference to the direction of travel of said screen belt, said heating means including an electric circuit of which the heated portion of said screen belt forms a bridging part.

8. Screen. printing machine comprising a belt conveyor having a planiform flight for removably supporting a workpiece, and a screen head superposed with respect thereto comprising side frame members having a screen ,belt revolubly supported therebetween with a substantially planiform flight substantially parallel to the planiform flight of said conveyor providing a space for the workpiece therebetween, a transversely disposed squeegee pressing the inner face of said screen belt to make line contact with the workpiece and force fluent material through said screen belt upon the workpiece, trunnions at one end of said frame members swingably and removably supporting said screen head, lifting jacks under the opposite ends of said frame members for tiltably adjusting said screen head about said trunnions, and means for driving said conveyor and said screen belt at substantially the same surface speed.

9. Screen printing machine comprising a belt conveyor having a planiform flight for removably supporting a workpiece, and a screen head superposed with respect thereto comprising side frame members having a screen belt revolubly supported therebetween with a substantially planiform flight substantially parallel to the planiform flight of said conveyor providing a space for the workpiece therebetween, a transversely disposed squeegee pressing the inner face of said screen belt to make line contact with the workpiece and force fluent material through said screen belt upon the workpiece, trunnions at one end of said frame members swingably and removably supporting said screen head, lifting jacks under the opposite ends of said frame members for tiltably adjusting said screen head about said trunnions, and means for driving said conveyor and said screen belt at substantially the same surface speed, said conveyor being swingably supported at the end adjacent the trunnions of said screen head and lifting jacks under the opposite end of said conveyor for swingably adjusting said conveyor relative to said screen head whereby the distance between'their substantially parallel flights may be varied.

10. Screen printing machine comprising an endless belt conveyor adapted to removably support a workpiece, a pair of spaced rollers over which said conveyor travels, said rollers being positioned to provide a planiform flight for said conveyor, each of said rollers being provided with sprockets-on the opposite ends thereof, chains co'operatingwith said sprockets, means to secure'said conveyor to said chains, means to drive at least one of saidsprockets, a screen head superposed with respect to and spaced from said conveyor to permit passage of the workpiece thereunder, said screen head comprising a frame having a plurality of rollers mounted therein, an endless screen belt passing over said rollers, said rollers being positioned to provide a planiform flight for the screen belt substantially parallel to said conveyoneach of said rollers having sprockets at the opposite sides'thereof, chains cooperating with said sprockets, means to secure to and maintain said screen belt taut be tween said chains, means to drive at least one of said sprockets to provide a surface speed to the screen belt substantially equal to that of the conveyor, means to tiltably adjust said screen head and a transversely disposed squeegee pressing the inner face of said screen belt to make line contact with the workpiece thereunder and force the decorating material through said screen belt upon said workpiece, said squeegee being positioned to provide the minimum eifect of lost motion'at the point of line contact.

11. Screen printing machine comprising an endless belt conveyor adapted to removably support a workpiece, a pair of spaced rollers over which said conveyor travels, said rollers being positioned to provide a planiform flight for said conveyor, each of said rollers being provided with sprockets on the opposite ends thereof, chains cooperating with said sprockets, means to secure said conveyor to said chains, means to drive at least one of said sprockets, a screen head superposed with respect to and spaced from said conveyor to permit passage of the workpiece thereunder, said screen head comprising a frame having a plurality of rollers mounted therein, an endless screen belt passing over said rollers, said rollers being positioned to provide a planiform flight for the screen belt substantially parallel to said conveyor, each of said rollers having sprockets at the opposite sides thereof, chains cooperating withsaid sprockets, means to secure to and maintain said screen belt taut between said chains, means to drive at least one of said sprockets positively from said-conveyor to provide a surface speed to the screen belt substantially equal to that of the conveyor, and a transversely disposed squeegee pressing the inner face of said screen belt to make line contact with the workpiece thereunder and force the decorating material through said screen belt upon said workpiece, said squeegee being positioned to provide the minimum effect of lost motion at the point of line contact.

12. Screen printing machine comprising an endless belt-conveyor adapted to removably support a workpiece, a pair of spaced rollers over which said conveyor travels, said rollers being positioned to provide a planiform flight for said to secure said conveyor to said chains, means to drive at least one of said sprockets, a screen head superposed with respect to and spaced from said conveyor to permit passage of the workpiece thereunder, said screen head comprising a frame having a plurality of rollers mounted therein, an endless screen belt passing over said rollers, said rollers being positioned to pro-' vide a planiform'flight for the screen belt substantially parallel to said conveyor, each of said rollers having sprockets at the opposite sides thereof chains cooperating with said sprockets,

means to secure to and maintain saidscreen 'end of said screen head for tiltably adjusting said screen head, and a transversely disposed squeegee pressing the inner face of said screen belt to make line contact with the workpiece thereunder and force the decorating material through said screen belt upon said workpiece;

13. Screen printing machine comprising an endless belt conveyor adapted to removably support a workpiece, a pair of spaced rollers over which said conveyor travels, said rollers being positioned to provide a planiform flight for said conveyor, each of said rollers being provided with sprockets on the opposite ends thereof, chains cooperating with said sprockets, means to'secure said conveyor to said chains, means to drive at least one of said sprockets, a screen head superposed with respect to and spaced from said conveyor to permit passage of the workpiece thereunder, said screen head comprising a frame having a plurality of rollers mounted therein, an endless screen belt passing over said rollers, said rollers being positioned to provide a planiform flight for the screen belt substantially parallel to said conveyor, each of said rollers having sprockets at the opposite sides thereof, chains cooperating with said sprockets, means to secure to and maintain said screen belt taut between said chains, means to drive at least one of said sprockets to provide a surface speed to the screen belt substantially equal to that of the conveyor, means to tiltably adjust said screen head, and a transversely disposed squeegee pressing the inner face of said screen belt to make line contact with the workpiece thereunder and force the decorating material through said screen belt uponv said workpiece.

14. Screen printing vmachine comprising an endless belt conveyor adapted to removably support a workpiece, a pair of spaced rollers over which said conveyor travels, said rollers being positioned to provide a planiform flight for said conveyor, each of said rollers being provided with sprockets on the opposite ends thereof, chains cooperating with said sprockets, means to secure said conveyor to said chains, means to drive at least one of said sprockets, a screen head superposed with respect to and spaced from said conveyor to permit passage of the workpiece thereunder, said screen head comprising a frame having a plurality of rollers mounted therein, an endless screen belt passing over said rollers, said rollers being positioned to provide a planiform flight for the screen belt substantially parallel to said conveyor, each of said rollers having sprockets at the opposite sides thereof, chains cooperating with said sprockets, means to secure to and maintain said screen belt taut between said chains, means to drive at least one of said sprockets to provide a surface speed to the screen belt substantially equal to that of the conveyor, trunnions at one end of said frame swingably supporting said screen head, lifting jacks cooperating with the opposite end of said screen head for tiltably adjusting said screen head, means to adiust said conveyor in accordance with the adjustment of the screen head to maintain the parallel flights of said conveyor and 10 screen belt when the distance therebetween is varied, and a transversely disposed squeegee pressing the inner face of said screen belt to make line contact with the workpiece thereunder and force the decorating material through said 15 screen belt upon said workpiece.

15. Screen printing machine comprising an endless belt conveyor adapted to removably support a workpiece, a pair of spaced rollers over which said conveyor travels, said rollers being 20 positioned to provide a planiform flight for said conveyor, each of said rollers being provided with sprockets on the opposite ends thereof, chains cooperating with said sprockets, means to secure said conveyor to said chains, means to drive at 25 least one of said sprockets, a screen head superposed with respect to and spaced lrom said conveyor to permit passage 01' the workpiece thereunder, said screen head comprising a frame having a plurality of rollers mounted therein, an endless screen belt passing over said rollers, said rollers being positioned to provide a planiform flight for the screen belt substantially parallel to said conveyor, each of said rollers having sprockets at the opposite sides thereof, chains cooperating with said sprockets, means to secure to and maintain said screen belt taut between said chains, means to drive at least one of said sprockets to provide a surface speed to the screen belt substantially equal to that ofthe conveyor, means to tiltably adjust said screen head, means to adjust said conveyor in accordance with the adjustment of the screen head to maintain the parallel flights of said conveyor and screen belt when the distance therebetween is varied, and a transversely disposed squeegee pressing the inner face of said screen belt to make line contact with the workpiece thereunder and force the decorating material through said screen belt upon said workpiece.

ERNEST K. SNYDER. 

